// By: arman jafarnejad - cppapps.blog.ir
#include<iostream>
#include<math.h>
#include<conio.h>
using namespace std;
int main()
{
   int a;
   int b;
   int c;
   c=0;
   cin>> a;
   b=1;
   
   while(a>0)
   {
         
      
             
         b=b*a;
            a--;
         }
         cout<< b;
         
   getch();
   return 0;
}